The invention concerns a press cage bar for a device for expressing liquids, which is bounded by at least one pressing edge in the area of a wear surface of a hard layer and which, in the area of at least one lateral face of the body of the cage bar, has at least one spacer that is raised above the lateral face.
The invention also concerns a device for expressing liquids, which has at least one press cage bar, which is bounded by at least one pressing edge in the area of a wear surface of a hard layer and which, in the area of at least one lateral face of the body of the cage bar, has at least one spacer that is raised above the lateral face.
Press cage bars of the aforementioned type are used as devices for expressing liquids from materials placed in the device. It can be used, for example, to express liquid substances from animal carcasses, offal, or oil-bearing fruits. The pressing devices have a drum-like design, and the press cage bars extend in the longitudinal direction of the drum. The substances to be processed are conveyed in this longitudinal direction. The residual materials are discharged in a practically moisture-free state from the inside of the drum at a drum discharge opening. The material is conveyed through the drum by a pressure and conveying screw.
During the conveyance of the materials through the drum, the liquids contained in the feed materials are expressed by the pressing operation between the contact surfaces of the screw channels of the conveying screw and the cage bars. To allow the expressed liquids to flow off, the cage bars are spaced apart to form drainage slits between them. To ensure optimum flow of the pressing operation, the cross-sectional area of the screw channel decreases from the inlet to the outlet.
The slits between the press cage bars are usually preset by spacers. In accordance with previously known embodiments, the spacers are, for example, placed manually as thin spacer plates; it is also already well known that thin spacer plates of this type can be joined with the cage bars by spot welding. However, due to the considerable forces that act during the pressing operation, these methods of installation of the spacers have the disadvantage that he spacers can be caused to slip, which can result in complete detachment of the cage bars and can cause the spacers to fall out. The use of spot welding also fails to provide adequate protection against slipping due to the danger of the welds tearing off.
In accordance with another well-known production method, the spacers are formed as single pieces with the cage bars and are produced by removing the excess material by milling or grinding. This production method prevents slipping and produces a high degree of stability of the overall device. However, in view of the large number of press cage bars that are used, this significantly increases production costs compared to the use of loose spacers.
It is already known from DE 298 11 871 U1 that cage bars can be provided with spacers that have increasing thickness starting from a wear surface and moving towards an underside of the body of the cage bar. In addition, the wear surface also has an inclined orientation.
It is known from DE 201 04 282 U1 that rivets with angled heads can be placed in a cage bar in such a way that they form spacers. The rivets have round-contoured rivet heads and are dimensioned in such a way that the rivet heads are spaced some distance from both the wear surface and an underside of the body of the cage bar.
U.S. Pat. No. 3,126,820 describes the installation of a plurality of cage bars in a pressing device. In this case, the spacers are provided with projecting stubs that fit into blind holes in the cage bars.